This paper describes experimental and analytic studies on pressure rise and propagation phenomena due to high current arcs in a container with opened pipes. The shape of experimental container is decided taking into account of underground common ducts. First, the arcs were ignited in the container with varying diameter D and length L of the opened pipes under the condition of arc current of 4 to 12.5kA and the arc duration of 0.1s. Based on measured waveforms, the maximum value of pressure rise Pmax and the pressure oscillation frequency Posc were obtained. As the result, it emerged that there is a tendency that Pmax becomes high with lessened D and elongated L. Moreover, D has a much greater impact on Pmax. And it emerged that the tendency of Posc with changing D and L can be explained by Helmholtz resonance approximately. Secondly, CFD model for the container with opened pipe was developed based on the experimental results, and simulations were carried out. Consequently, simulation results were found to correspond to the experimental pressure rise.